Top 10 Mistakes Java Developers need to avoid

Common mistakes that Java developers need to avoid; coding without a plan, trying to memorize the code, using raw type, neglecting existing libraries, etc.

Digital Delivery
12 min
Digital Delivery
Top 10 Mistakes Java Developers need to avoid

Java is a popular programming language that allows you to build robust and scalable software. Java is a multi-paradigm language that enables users to develop systems using object-oriented, functional, or aspect-oriented programming.

One of the reasons Java has become such a widely adopted programming language is that it eliminates many of the complexities that previously existed when using other programming languages.

Before Java, programs such as Python, C++, and others let you develop software quickly; Java took it a step further by incorporating libraries with pre-coded solutions.

With all the Java advantages and resources available, Java developers still face many common mistakes. Here are ten of the most common Java design mistakes developers make.

java mistakes that developers need to avoid.

1. Coding Without a Plan

One of the most common Java design mistakes happens when designers begin a project without a set plan in place. Having a clear Java design plan is crucial as it helps developers decide the semantics - what they should do and how they should approach the Java programming project.

If a programmer or Java designer does not have a set Java design plan, they may create complex applications that are difficult to maintain.

In the corporate setting, Software Engineers and other Developers need to meet timelines and be able to show their action plans to stakeholders.

Practice planning from day one and you won't regret it.

2. Trying to Memorize Code

Second on our list of common Java design mistakes is the attempt to remember the code without referencing notes.

Developers who simply memorize code without understanding it usually struggle to adapt their code for new situations, which ultimately wastes time and can introduce errors.

They may also not comprehend code written by others, which means collaboration becomes difficult. Java developers should avoid memorizing code and instead focus on understanding the code they are working with.

When developing Javascript applications, programmers should write down all relevant information as comments when needed or ask someone else with plenty of experience using Java coding standard library classes/methods as references!

Developers can also use Java API documentation pages for Java classes and methods if they are unsure how things work.

3. Using Raw Type Instead of a Parameterized

Using raw type instead of parameterized is third on the list of our common Java design mistakes. Designers use raw type sometimes instead of Java generics to define the type of data inserted into a container. J

ava generics allow developers to create classes and methods that work with any data type, including arrays, lists, and maps. When using raw types instead, code becomes less flexible and more prone to errors.

A Parameterized type is a Java language feature that lets you specify the type parameters for a generic class or interface. The compiler then infers the actual concrete types for those parameters when instantiating the generic class or interface.

Java designers should use parameterized types instead of raw types when working with generics.

For example, Java Designers can create a list that contains Java objects using the following line of code: List names = new ArrayList();

This code creates an empty array list that only stores generic Object references. If you want to add different items into this array list, you need to call the Java Collection API and wrap it in a collection such as LinkedHashSet or TreeSet.

This solution is not ideal because it forces developers to cast from one class to another during runtime, which can lead to errors caused by Java design mistakes.

4. Neglecting Existing Libraries

The fourth on the list of Java design mistakes occur when designers ignore the open-source libraries available.

Java developers should always take advantage of Java libraries as they've been created by experienced designers who have dealt with the same problems you may face.

Instead of writing code from scratch, Java programmers should use these existing Java libraries to avoid wasting time creating unnecessary Java classes.

TOP Java libraries among others include;

5. Ignoring Causes of Compile Time Errors

Often, simple mistakes committed by Java programmers when writing code can result in compile-time errors. Compile-time errors are syntax errors found by the Java compiler during the compilation process.

Java developers should always take time to review their code and look for compile-time errors as they can help you find mistakes in your Java source code before it's run.

A common compile-time error that Java designers face is using the wrong variable type when declaring a variable or assigning incompatible data types together.

6. Having Null pointers

Null pointers are Java objects that represent a pointer to no object. Java code can be written so that the programmer is unaware of a null value assigned to a particular variable.

This can often lead to runtime errors, as Java will try to access members or methods on the null object, which will result in an error.

Because a NULL character has a Boolean value, Java designers should take care when working with Java strings, Java arrays, and Java collections.

A common example of the Null Pointer error is, String firstName = "John"; // Line A System.out.println(firstname); // Line B /* Output will be NULL */.

This can cause unexpected behavior in your Java application if you are not careful about checking for null values before accessing them.

C/C++ programs that use pointers may crash with a segmentation fault if you try to dereference a null pointer. Other languages, such as Java and Python, throw NullPointerExceptions when they encounter a null object reference.

Still, the issue is that the RuntimeException may be raised at almost every line of code. A static type system can declare references, which are guaranteed not to be null.

7. Forgetting to Free Resources

The next on our list of java design mistakes is when Java programmers forget to free up resources, leading to memory leaks and other performance issues down the road.

Compatibility issues may arise if you don't release resources promptly.

Java developers can free up resources by automatically deleting any unused Java objects from memory by using Java garbage collection.

The Java garbage collector is a built-in Java class that helps to reclaim the memory occupied by unreferenced Java objects.

8. Allowing Memory Leaks

Memory leaks are what programmers need to be aware of primarily because Java provides automatic memory management features. This can often lead to programmers neglecting to check on the memory manually.

Sometimes objects can be referred to unnecessarily, leading to Java memory leaks. Java developers should always manually check on their Java program and make sure there are no unnecessary references, avoiding performance issues down the road due to Java design mistakes. Read more on Java memory management.

9. Not Using Design Patterns

Design patterns are indispensable for Java programmers, as they can help programs run more efficiently by implementing standard design solutions in a particular problem domain.

These long-established techniques work well with most of the Java design mistakes you may face when writing code for applications or systems, which is why it's essential to know how to use them properly.

Not using Java design patterns can lead to inefficient Java code, so ensure you're familiar with the most common Java design patterns before starting your next project.

10. Ignoring Exceptions

The final of our ten most common Java design mistakes is ignoring exceptions. An exception is an object that explains what went wrong during object-oriented programming.

Exceptions can happen for several reasons, and when they do, pay attention and understand why they've happened.

If you ignore exceptions, it can cause your application to crash, which will cost you time while the issue is resolved or, worse - it can lead to data loss.

Java programmers should always make sure they handle exceptions properly, so their Java applications do not run into future problems.


Being a Java programmer and designer can be challenging, and mistakes will happen, whether you are brand new or seasoned.

Fortunately, there are thousands of online tutorials and resources to teach you language design and other Java-related skills that are needed to succeed and help you avoid Java design mistakes.

If you know these common Java design mistakes, you can be proactive and reduce your Java development time while producing higher-quality applications. Understanding these mistakes allows you to debug HTML, Java, and JavaScript code problems.

If you are looking for additional information or assistance on how to avoid the above-mentioned and other possible Java mistakes, reach out to our team of experts.

Published on
February 21, 2022

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